Ternary phase diagram of model dentin adhesive exposed to over-wet environments

When adhesives and/or composites are bonded to the tooth,water in the environment can interfere with proper interface formation. formation of water blisters and phase separation at the adhesive/dentin interface have appeared as new types of bond defects. to better understand this problem,we determined the near-equilibrium partition of the hydrophobic/hydrophilic components when exposed to over-wet environments. model methacrylate-based adhesives were mixed with different amounts of water to yield well-separated aqueous and resin phases. it was found that less than 0.1% bisgma but nearly one-third of the hema diffused into the aqueous phase,leaving the remaining resin phase relatively hydrophobic. a partial phase diagram was created for the ternary bisgma/hema/water system. all the experimental phase partitioning data were plotted,and the points lay on a binodal curve that separated the single-phase region from the two-phase region. we obtained the 3 tie lines by connecting the 2 points of each conjugate pair of the phase partitioning data from the 3 sets of tripartite mixtures. information about solubility,water miscibility,distribution ratio,and phase partitioning behavior could be obtained quantitatively. this type of phase diagram will provide a more thorough understanding of current adhesive performance and elucidate directions for further improvement. © 2011 international & american associations for dental research.